Using high-capacity accumulators and accumulator modules is associated with a problem of ratio between the increasing accumulator power and weight vs. room available for removal of heat generated in chemical reactions during the accumulator charging and discharging. Any major overheating of the accumulator can result in a fire or explosion. Operation of the accumulator outside the safe temperature range can also significantly reduce the accumulator service life. Maintaining the operating temperature in a safe range to eliminate the above-described accidents requires additional equipment to ensure greater exchange of heat. Such equipment may also be required where extremely low temperatures reduce the accumulator power substantially and it is necessary to raise the operating temperature by heat exchange.
One possible solution to cooling of a set of batteries offers PCT application WO2006124663. The application describes a substrate, respective a body into which the groups of battery units are placed creating a battery set resistant to vibrations, and further shows heat transfer medium pipes passing through the battery set.
A similar solution with a somewhat different arrangement of battery units and heat transfer tubes passing along the individual sections of the battery units is disclosed in WO2010028692. In both described systems, the heat is transferred from the accumulator casing, not directly from its interior space. This logically reduces the heat exchange rate between the battery core and the cooling medium.
According to the German patent application No. DE 10 2008 034 867, the accumulator cooling is provided by the current collectors on cells consisting of thin film planar lithium electrodes. The collectors transfer the heat losses from the battery via an electro insulating, thermally conductive film to a heat exchange plate on the top of the accumulator, which can optionally be connected to a vehicle cooling system. In this arrangement, the heat is removed through the current collectors directly from inside of the accumulator. The problem still is in further transfer of heat from such folio current collectors to the actual heat exchange system. Moreover, the heat transfer is reduced by using an electro insulating film and the heat transfer capacity is limited to a single heat exchange plate.
PCT application WO WO2010031363 discloses a lithium accumulator comprising metal frames arranged in a stack, where each frame contains a puncture, in which one thick three dimensional (3D) electrode is placed, and whereby the electrodes of opposite polarity are separated by separators and the frames with electrodes of opposite polarity are isolated from each other. Although the metal frames allow better heat transfer from the inside of the accumulator stack, they do not guarantee a reliable heat transfer from large-sized electrodes and especially from modules with number of stacks arranged side by side. I